Variable angle spinal surgery instrument

ABSTRACT

An instrument for use in a procedure for inserting a spinal implant between human vertebrae may include a shaft and an end member. The end member may rotate with respect to the shaft. An angle of the end member with respect to the shaft may be varied when the end member is in a disc space between the human vertebrae. The instrument may include a slide for securing the end member at selected angles relative to the shaft. The end member may be separable from the shalt when the end member is in a selected orientation with the shaft. An instrument kit may include a shaft assembly and modular end members for various steps in a surgical procedure, such as disc space preparation, disc space evaluation, and spinal implant insertion.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of, and claims a benefit of priorityunder 35 U.S.C. 120 of the filing date of U.S. patent application Ser.No. 11/257,745 by inventors Margaret M. Hunt et al. entitled “VariableAngle Spinal Surgery Instrument” filed on Oct. 25, 2005, which in turnclaims the benefit of priority under 35 U.S.C. §119 to provisionalpatent application No. 60/623,274 filed Oct. 29, 2004; and is acontinuation in part of, and claims a benefit of priority under 35U.S.C. 120 of the filing date of U.S. patent application Ser. No.10/633,371 by inventors Scott A. Webb et al. entitled “Spinal Implant”on Aug. 1, 2003, the entire contents of which are hereby expresslyincorporated by reference for all purposes.

BACKGROUND

1. Field of Invention

The present invention generally relates to the field of medical devices.Some embodiments of the invention relate to instruments used duringsurgical procedures to install a spinal implant in a human spine. Someembodiments of the invention relate to instruments used in evaluatingand/or preparing a disc space for a spinal implant. Some embodiments ofthe invention relate to an instrument used to manipulate and/or positiona spinal implant between human vertebrae.

2. Description of Related Art

An intervertebral disc may degenerate. Degeneration may be caused bytrauma, disease, and/or aging. An intervertebral disc that becomesdegenerated may have to be partially or fully removed from a spinalcolumn. Partial or full removal of an intervertebral disc maydestabilize the spinal column. Destabilization of a spinal column mayresult in alteration of a natural separation distance between adjacentvertebrae. Maintaining the natural separation between vertebrae mayprevent pressure from being applied to nerves that pass betweenvertebral bodies. Excessive pressure applied to the nerves may causepain and/or nerve damage. During a spinal fixation procedure, a spinalimplant may be inserted in a space created by the removal or partialremoval of an intervertebral disc between adjacent vertebrae. The spinalimplant may maintain the height of the spine and restore stability tothe spine. Bone growth may fuse the implant to adjacent vertebrae.

A spinal implant may be inserted during a spinal fixation procedureusing an anterior, lateral, posterior, or transverse spinal approach. Adiscectomy may be performed to remove or partially remove a defective ordamaged intervertebral disc. The discectomy may create a space for oneor more spinal implants. The amount of removed disc material maycorrespond to the size and type of the spinal implant or spinal implantsto be inserted.

Spinal surgery may be complex due in part to the proximity of the spinalcord and/or the cauda equina. Preparation instruments and spinalimplants may need to be carefully inserted to avoid damage to nervetissue. Alignment and spacing of a spinal implant that is to be insertedinto a patient may be determined before surgery. Achieving thepredetermined alignment and spacing during surgery may be important toachieve optimal fusion of adjacent vertebrae.

U.S. Pat. No. 6,682,534 to Patel et al., which is incorporated byreference as if fully set forth herein, describes an endplatepreparation instrument for preparing endplates of adjacent vertebralbodies. The instrument includes an elongated member that rotates in ahousing member. The elongated member includes a cutting element thatpenetrates and removes bone from the endplates when the elongated memberis rotated.

U.S. Pat. No. 6,599,294 to Fuss et al., which is incorporated byreference as if fully set forth herein, describes a surgical instrumentfor introducing a spinal implant between two vertebrae. The instrumentincludes two mutually opposing guide bodies. The guide bodies combine toform a guideway for lateral insertion of a spinal implant in theintervertebral space.

Some spinal implants may be inserted using a lateral (transverse)approach. U.S. patent application Ser. No. 10/633,371 to Mitchell atal., which is incorporated by reference as if fully set forth herein,describes spinal implants that may be inserted using a lateral(transverse) approach.

SUMMARY

An instrument may be used in a procedure to insert a spinal implant. Insome embodiments, the spinal implant may be inserted into anintervertebral disc space. The spinal implant may provide stability andpromote fusion of adjacent vertebrae. In an embodiment, an instrumentmay include a shaft assembly and an end member. The end member mayrotate with respect to the shaft assembly. In some embodiments, an angleof the end member relative to the shaft assembly may be varied while theend member is in a disc space. The ability to rotate an end memberrelative to a shaft assembly may simplify and facilitate positioning ofthe end member at a desired location in the disc space. The ability torotate the end member relative to the shaft assembly may decrease thesize of an incision and opening needed to provide room for preparing adisc space and inserting a spinal implant in the disc space.

In certain embodiments, an instrument set for a spinal fusion proceduremay include end members that are coupled to shaft assemblies such thatseparation of the end members from the shaft assemblies is inhibited.The end members may be coupled to the shaft assemblies by rivets, pressfit connections, adhesives, or other fastening systems. An end membermay be rotated and set in desired positions relative to a shaft assemblyprior to insertion of the end member into a patient and during use ofthe end member.

In certain embodiments, an instrument set may include a shaft assemblyand modular end members. Various end members may be removably coupled tothe shaft assembly. The instrument set may include end members forvarious steps in a procedure for installing a spinal implant, such asdisc preparation, disc space evaluation, and implantation.

In some instrument embodiments, an end member of an instrument may beseparable from a shaft assembly of the instrument when the end member isplaced in a selected orientation relative to the shaft assembly. An endmember may include a slot. A portion of the shaft assembly may engagethe slot to allow the end member to be selectively coupled to orseparated from the shaft assembly.

In some instrument embodiments, a shaft assembly of an instrument mayinclude a slide. The slide may engage an end member of the instrument tosecure the end member at a selected angle with respect to the shaftassembly. The slide and the end member may include cooperative captureelements. The capture elements may engage to inhibit rotation of the endmember with respect to the shaft assembly. In some embodiments, thecapture elements may be frictional surfaces. In some embodiments, thecapture elements include meshing teeth that form an interference fit toinhibit undesired rotation of the end member relative to the shaftassembly. The shaft assembly may include a locking member to lock aslide in position against an end member. In certain embodiments, a shaftassembly may include a biasing member to urge a slide into engagementwith an end member.

In some embodiments, an end member of an instrument may be a rasp forabrading surfaces of vertebrae adjacent to a disc space. Upper and lowersurfaces of the rasp may be textured to cut vertebral bone. In anembodiment, a surgeon may vary an angle of the rasp with respect to ashaft assembly while the rasp is in the disc space to selectivelyposition the rasp relative to the vertebrae.

In certain embodiments, an end member of an instrument may be a trialmember for evaluating a size and/or shape of a disc space. An instrumentset may include trial members of various sizes that can be removablycoupled to a shaft assembly. Sizes of the trial members may correspondto the sizes of implants available to a surgeon. In an embodiment, asurgeon may vary an angle of the trial member with respect to the shaftassembly to facilitate positioning of the trial member in the discspace.

In some embodiments, an end member of an instrument may be a tamp forpositioning a spinal implant in a disc space. The tamp may include anend that engages the spinal implant to advance the spinal implant in thedisc space. In an embodiment, a surgeon may vary an angle of the tampwith respect to a shaft assembly during insertion to facilitatepositioning of the spinal implant in a desired location.

In certain embodiments, an angle of an end member relative to a shaftassembly may be controlled during a surgical procedure to allow aproximal end of a shaft assembly to be maintained in a relatively smallrange at an incision at a surface of the body. The angle of the endmember relative to the shaft assembly may be adjusted at selected pointsof advancement of the instrument into a disc space. The angle of the endmember relative to the shaft assembly may also be adjusted duringremoval of the end member from the disc space.

In some embodiments, an end member may be secured at a first anglerelative to a shaft assembly. An end member may be moved to a firstposition along a path in a disc space while the end member is secured atthe first angle. A capture element of the end member may be disengagedto allow the end member to rotate with respect to the shaft assembly.The angle of the end member with respect to the shaft assembly may beadjusted to a second angle. The end member may be secured to the shaftassembly at the second angle. The end member may be advanced to a secondposition on the path while the end member is secured at the secondangle. The end member may be successively adjusted and advanced untilthe end member is in a desired position in the disc space.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will become apparent to thoseskilled in the art with the benefit of the following detaileddescription and upon reference to the accompanying drawings in which:

FIG. 1 depicts a perspective view of an embodiment of an instrumentincluding a shaft assembly and a separable end member.

FIG. 2 depicts a perspective view of an embodiment of an instrument witha non-separable end member.

FIG. 3 depicts a front view of an embodiment of a shaft assembly.

FIG. 4 depicts a side view of an embodiment of a shaft assembly.

FIG. 5 depicts a cross-sectional view of the embodiment of the shaftassembly, taken substantially along line 5-5 of FIG. 4.

FIG. 6 depicts a detail view of the embodiment of the locking membershown in FIG. 5.

FIG. 7 depicts a detail view of an embodiment of a locking mechanism.

FIG. 8 depicts a detail view of an embodiment of a distal portion of ashaft assembly in a closed position.

FIG. 9 depicts a detail view of an embodiment of a distal portion of ashaft assembly in an open position.

FIG. 10 depicts a detail view of an embodiment of teeth on a collar of ashaft.

FIG. 11 depicts an end view of an embodiment of a collar of a shaft.

FIG. 12 depicts a perspective view an embodiment of a shaft assemblywith a portion of a bias section of the shaft assembly shown in cut-awayto show a biasing member of the shaft assembly.

FIG. 13 depicts a top view of an embodiment of a rasp.

FIG. 14 depicts a front view of an embodiment of a rasp.

FIG. 15 depicts a top view of an embodiment of a trial member.

FIG. 16 depicts a front view of an embodiment of a trial member.

FIG. 17 depicts a top view of an embodiment of a tamp.

FIG. 18 depicts a front view of an embodiment of a tamp.

FIGS. 19A-19D depict schematic representations of installation of an endmember onto a shaft assembly.

FIGS. 20A-20E depict-schematic representations of use of a rasp toprepare a disc space.

FIGS. 21A-21D depict schematic representations of use of a tamp toposition a spinal implant in a disc space.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Thedrawings may not be to scale. It should be understood that the drawingsand detailed description are not intended to limit the invention to theparticular form disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the present invention as defined by the appendedclaims.

DETAILED DESCRIPTION

An instrument may be used in a procedure to insert a spinal implantbetween human vertebrae. In an embodiment, the instrument may include ashaft assembly and an end member. The end member may rotate (e.g., pivotor angulate) with respect to the shaft assembly. The shaft assembly mayinclude a slide that engages the end member to secure the end member ata selected angle with respect to the shaft assembly. To facilitate useof the instrument, the angle of the end member relative to the shaftassembly may be adjusted while the end member is in use in a patient.

Components of instruments may be made of materials including, but notlimited to, metals, ceramics, and/or polymers. The metals may include,but are not limited to, stainless steel, titanium, and titanium alloys.Some components of instruments may be autoclaved and/or chemicallysterilized. Components that may not be autoclaved and/or chemicallysterilized may be made of sterile materials.

In some embodiments, an instrument may include end members that arecoupled to shaft assemblies such that separation of the end members fromthe shaft assemblies is inhibited. The end members may be coupled to theshaft assemblies by rivets, press fit connections, adhesives, threadedconnectors or other fastening systems. An end member may be rotated andset in desired positions relative to a shaft assembly prior to insertionof the end member into a patient and during use of the end member.

In some embodiments, an instrument set may include a shaft assembly andmodular end members. The end members may be removably coupled to theshaft assembly. An instrument set may include different end members forvarious steps of a procedure, including, but not limited to,distraction, disc preparation, disc space evaluation, and implantation.End members used for disc preparation may include, but are not limitedto, rasps, trials, chisels, curettes, or distractors. End members usedfor implantation may include, but are not limited to, inserters, tamps,or guides.

An instrument including an adjustable end member may allow preparationof a disc space and insertion of a spinal implant between humanvertebrae to be effected from above an incision in a patient through arelatively small opening in the patient. The instrument may allowsimple, efficient, and safe preparation of a disc space for receiving aspinal implant, including preparation of the contralateral (opposite)side of the disc space. The instrument may allow spinal implantinsertion through a relatively small opening in the patient whilemaintaining maneuverability and visibility of the surgical site, spinalimplant, and instruments during the procedure.

FIG. 1 depicts a perspective view of an embodiment of instrument 50.Instrument 50 may include shaft assembly 52 and end member 54. Endmember 54 may be pivotably coupled to shaft assembly 52. In someembodiments, end member 54 may be separable from shaft assembly 52.Shaft assembly 52 may be included in a modular instrument set having oneor more end members.

Shaft assembly 52 may include shaft 56, slide 58, handle 60, lockingmember 62, and connector 64. Handle 60 may be coupled to shaft 56. Insome embodiments, slide 58 of shaft assembly 52 is able to movelongitudinally relative to shaft 56. A distal portion of slide 58 mayengage an end member to inhibit undesired rotation of the end memberrelative to shaft 56. Locking member 62 may limit movement of shaft 56relative to slide 58 to fix an angular position of an end member coupledto shaft assembly 52. As used herein, “slide” includes any element thatmoves (e.g., translates and/or rotates) with respect to another element.The slide may be positioned outside, inside, or along side the otherelement. A slide may be, but is not limited to, a shaft, a tube, a rod,a bar, a beam, or a combination thereof. In certain embodiments, a slidemay threadably engage another element.

As shown in FIG. 1, slide 58 may be an outer shaft that surrounds aportion of shaft 56. Distal end 66 of slide 58 may engage end member 54to hold the end member at a desired angle relative to shaft 56. Lockingmember 62 may be coupled to slide 58. Locking member 62 may be operatedto control axial position of slide 58 relative to shaft 56. In someembodiments, locking member 62 may include a spring or other biaselement that applies force to move slide 58 towards connector 64 ofshaft 56.

In some embodiments, shaft 56 of instrument 50 may be a single member.In certain embodiments, a shaft may include multiple members. Distalportion 68 of shaft 56 may include connector 64. Connector 64 may beoriented perpendicular to a longitudinal axis of shaft 56. Connector 64may form a “tee” shape in distal portion 68 of shaft 56.

End member 54 may include body opening 70, and surfaces 72, 74. Endmember 54 may be coupled to connector 64 of distal portion 68 of shaft56. Pivoting end member 54 relative to shaft 56 about connector 64 mayallow the end member to be positioned at various angles relative to theshaft during use of instrument 50. A rotational range of motion of endmember 54 relative to shaft assembly 52 may be limited by a surface ofthe end member that defines opening 70. In some embodiments, the surfaceof the end member that defines opening 70 is a planar surface so thatthe range of motion of end member 54 relative to shaft assembly 52 is180°. In other embodiments, the surface of the end member that definesopening 70 may be angled or curved so that the range of motion of endmember 54 relative to shaft assembly 52 is less than or greater than180°.

In some embodiments, end member 54 may be separable from shaft assembly52. In certain embodiments, end member 54 may be separated from shaftassembly 52 when the end member is in a selected orientation withrespect to the shaft assembly. For example, end member 54 may beseparable from shaft assembly 52 when distal portion 68 of shaft 56 isaligned in slot 76. To separate end member 54 from shaft assembly 52,end member 54 may be rotated about connector 64 until distal portion 68of shaft 56 is aligned in slot 76. Slide 58 may be retracted fromconnector 64, and end member 54 may be removed from distal portion 68.

In some embodiments, slide 58 and end member 54 may includecomplementary capture elements. As used herein, “capture element”includes any element that directly or indirectly contacts or engagesanother element to at least partially inhibit relative motion (e.g.,translation, rotation) of the elements. A capture element may include,but is not limited to, a detent, a spring, a groove, a ridge, a tab, apin, a projection, a slot, a hole, a notch, roughened or texturedsurfaces or threading. For example, as shown in FIG. 1, slide 58 mayinclude teeth 78 and end member 54 may include complementary teeth 80. Acapture element may be a separate component or may be a part of anotherelement. In some embodiments, a capture element may automaticallyrelease when a predetermined amount of force is applied to the elementthat is captured. In other embodiments, release of a capture element mayrequire a separate action by a user (e.g., user actuated movement of theslide relative to the shaft).

Capture elements may be positioned over a subset of the range that endmember 54 is able to rotate relative to shaft assembly 52 to define aninstrument use range of the end member relative to the shaft assembly.In some embodiments, teeth 80 may be formed on end member 54 so that theinstrument use range of the end member relative to the shaft assembly isfrom about 20° to about 180°, where 0° is the angle formed between theshaft assembly and the end member when a shaft of the shaft assembly ispositioned in slot 76 such that the shaft assembly can be removed fromthe end member. In other embodiments, the instrument use range of theend member relative to the shaft assembly may be less or greater thanthe range of 20° to 180° (e.g., 30° to 180°, 10° to 180°, 10° to 190°,45° to 135°).

In some embodiments, a slide of a shaft assembly may include detents orpins that engage holes or slots in an end member. In other embodiments,a slide of a shaft assembly may include holes or slots that engagedetents or pins on an end member. In some embodiments, engaging surfacesof a slide and/or end member may be textured to inhibit relative motionbetween a shaft assembly and an end member when the slide is biasedagainst the end member.

In an embodiment, turning (e.g., clockwise rotation) locking member 62in a first direction (e.g., clockwise) may move slide 58 toward endmember 54. Distal end 66 of slide 58 may engage end member 54. Turninglocking member 62 in an opposite direction (e.g., counterclockwise) maymove slide 58 away from end member 54. Distal end 66 of slide 58 maydisengage from end member 54. With distal end 66 disengaged from endmember 54, end member 54 may pivot with respect to shaft 56 aboutconnector 64.

FIG. 2 depicts an embodiment of instrument 50 that has end member 54fixed to shaft assembly 52. Connector 64 may be a pin that is press fitinto end member 54. A portion of the pin passes through shaft 56 so thatend member is able to rotate relative to shaft assembly 52 aboutconnector 64. Locking member 62 may move slide 58 so that captureelements of the slide engage with, or disengage from, capture elementsof end member 54.

FIG. 3 and FIG. 4 depict front and side views of an embodiment of shaftassembly 52. FIG. 5 depicts a cross-sectional view of an embodiment ofshaft assembly 52. Shaft 56 may include tip 82, body 84, and sleeve 86.Tip 82, body 84, and sleeve 86 may be coupled by various methodsincluding, but not limited to, application of an adhesive, welding,press-fitting, threading, pins, and/or rivets. Tip 82 may have anelongated section and connector 64. A cross-sectional shape of theelongated section perpendicular to the longitudinal axis of theelongated section may be substantially square. Handle 60 may be coupledto sleeve 86 and shaft 56 by a pin.

Slide 58 may include tube 88 and collar 90. In some embodiments, tube 88may have a substantially cylindrical outer surface. An opening throughcollar 90 may have a substantially square shape that corresponds to ashape of the elongated section of tip 82. The shape of the opening incollar 90 and the shape of the elongated section of tip 82 may inhibitrotation of slide 58 relative to shaft 56.

Slide 58 may include indicia 92. Indicia 92 may indicate insertion depthof an end member into a patient.

Handle 60 may be used to hold shaft assembly 52. In some embodiments,locking member 62 may be rotated with fingers of the same hand withwhich a user is holding handle 60. A top of handle 60 may be an impactsurface. A mallet or other impact instrument may strike the impactsurface to drive an end member coupled to the shaft assembly into a discspace. As shown in FIG. 5, some embodiments of handle 60 may includespring 94 and pin 96. An end of a slap hammer may include a keyway thatengages pin 96 to couple the slap hammer to shaft assembly 52. Spring 94may apply force to the slap hammer that holds the shaft assembly and theslap hammer together. The slap hammer may be used to remove an endmember from a disc space.

FIG. 6 depicts a detail view of an embodiment of locking member 62.Locking member 62 may include portions 62A and 62B. Portions 62A and 62Bmay be fixedly coupled (e.g., by adhesive, welding, threads, orsoldering) after the portions are properly positioned relative to shaft56 and slide 58. Capture washer 98 may be coupled to a distal end ofportion 62A. Capture washer 98 may engage rim 100 of slide 58 whenlocking member 62 is rotated to move the slide away from a connector ofthe shaft assembly. Belleville washers 102 may be positioned between endface 104 of slide 58 and end face 106 of portion 62B. When lockingmember 62 is rotated to move slide 58 towards connector 64 (depicted inFIGS. 3-5), end face 106 may push against Belleville washers 102.Belleville washers 102 may push against slide 58 to move the slidetowards the connector.

Threading 108 on portion 62B may mate with threading 110 of sleeve 86.Locking member 62 may be rotated in a first direction to move slide 58towards a connector of a shaft assembly. Teeth of the slide may engageteeth of an end member to fix the angular position of the end memberrelative to the shaft assembly. Locking member 62 may be rotated in anopposite direction to move slide 58 away from the connector. When theslide is moved away from the connector, teeth of the slide may disengagefrom teeth of the end member to allow the angular position of the endmember relative to the shaft to be changed.

To assemble shaft assembly 52 (depicted in FIGS. 3-5), collar 90 may beplaced on tip 82. Tip 82 may be welded to body 84. Retainer washer 98may be welded to portion 62A. Portion 62A may be placed on tube 88. Tube88 may be welded to collar 90.

Sleeve 86 may be press-fit into handle 60. Portion 62B may be threadedonto thread 110 of sleeve 86. Belleville washers may be placed aboutshaft 56. An opening in sleeve 86 may be aligned with an opening inshaft 56 and a pin may be press fit into the openings to couple thesleeve and handle 60 to the shaft. Portion 62A may be positioned againstportion 62B. Portion 62A and portion 62B may be welded together to formlocking member 62 and the complete shaft assembly.

FIG. 7 depicts a cross-sectional view of a portion of an embodiment of ashaft assembly. Capture washer 98 may be positioned on slide 58. A tipmay be placed in a collar. The tip may be coupled to a body. The bodymay be positioned in slide 58. The collar may be coupled to slide 58.Locking member 62 may be positioned on slide 58. An adhesive (e.g.,Loctite Engineering Adhesive) may be applied to threading of capturewasher 98. Capture washer 98 may be threaded on locking member 62.Sleeve 86 may be press fit in handle 60 so that an opening through thesleeve aligns with an opening through the handle. Sleeve 86 may bethreaded in locking member 62 until an opening in body 84 aligns withthe openings through the sleeve and handle 60. Pin 111 may be positionedin handle to fix the position of body 84 relative to sleeve 86 andhandle 60. Rotating locking member 62 advances or retracts slide 58relative to handle 60.

FIG. 8 depicts a distal portion of a shaft assembly when a lockingmember of the shaft assembly is rotated to drive slide 58 towardsconnector 64 of shaft 56. FIG. 9 depicts a distal portion of anembodiment of a shaft assembly when the locking member of the shaftassembly is disengaged to drive slide 58 away from connector 64 of shaft56.

FIG. 10 depicts a detail view of an embodiment of teeth 78 of collar 90of a slide. In some embodiments, collar 90 may include from 1 to about 8teeth 78. In an embodiment, collar 90 includes 4 teeth. In someembodiments, an angular spacing between teeth 78 may be from about 5 toabout 30°. In an embodiment, the angular spacing between teeth is about14°. In some embodiments, an angle between sides of tooth 78 may be fromabout 150° to about 5°. In an embodiment, the angle between sides of atooth is about 60°.

FIG. 11 depicts an end view of an embodiment of a collar of a slide.Opening 112 may receive a tip of a shaft of a shaft assembly. In someembodiments, opening 112 may have a shape other than square orrectangular, such as, but not limited to, circular, diamond-shaped, orhexagonal. A slide of an instrument may translate on a shaft withoutrotation of the slide relative to the shaft. Engaging surfaces of theshaft and the collar may inhibit rotation of the shaft with respect tothe collar. If a shape of an opening of the collar is circular, a shaftpositioned in the collar may include a slot. A pin may be press fit intothe slide through the slot so that rotation of the shaft relative to theslide is inhibited, while still allowing for axial movement of the sliderelative to the shaft.

In an embodiment, a shaft assembly may include a biasing member thaturges a slide toward a distal portion of a shaft assembly. A biasingmember may include, but is not limited to, a coil spring, Bellevillewashers, or an elastomeric member. FIG. 12 depicts shaft assembly 52including shaft 56 and slide 58. Shaft 56 may include a distal portionand a proximal portion. Distal portion 68 may include connector 64.Proximal portion 114 may include knob 116. Knob 116 may be an impactsurface that allows an end member that is coupled to connector 64 to bedriven into a disc space. Knob 116 may also be positioned against auser's palm or thumb during use to allow a user to move slide 58relative to shaft 56.

Shaft assembly 52 may include bias section 118. A portion of biassection 118 of FIG. 12 is shown in cut-away to reveal some of the innerfeatures of the bias section. Bias section 118 may include biasingmember 120, and grips 122. A first end of biasing member 120 may bepositioned against a portion of bias section 118. A second end ofbiasing member 120 may be positioned against ledge 124 of shaft 56. Insome embodiments, ledge 124 may be formed by reducing a diameter of aportion of shaft 56. In some embodiments, a ledge may be formed byplacing a weld bead or other obstruction on the shaft. In someembodiments, a ledge may be formed by a pin or washer coupled to theshaft. Biasing member 120 may provide a force to slide 58 that moves theslide towards connector 64 of shaft 56. A user may grasp grips 122 withfingers while knob 116 is positioned against the user's palm or thumb.Grips 122 may be pulled away from connector 64 to move slide 58 awayfrom the connector. When grips 122 are released, biasing member 120 maymove slide 58 towards connector 64.

An end member may be coupled to connector 64. Teeth 78 may engageportions of the end member to set a desired angle of the end memberrelative to shaft assembly 52. The angle of the end member relative tothe shaft assembly may be adjusted during use by repositioning slide 58relative to the end member.

In some embodiments, shaft assembly 52 may include lock 126. Lock 126may include thread that complements a threaded portion of shaft 56. Whenan end member that is coupled to connector 64 is at a desired anglerelative to shaft assembly 52, lock 126 may be rotated to position anend of the locking member against bias section 118. Positioning lockingmember 126 against biasing section 118 may inhibit movement of slide 58relative to the end member, thus inhibiting rotation of the end memberrelative to shaft assembly 52. When it is desired to change the angle ofshaft assembly 52 relative to the end member, locking member 126 may berotated to move the locking member away from bias section 118 so thatslide 58 can be moved to allow the teeth of the slide to be repositionedwith respect to the end member.

In an embodiment, an end member may be a rasp that is used to abradesurfaces of vertebrae. FIGS. 13 and 14 depict top and front views,respectively, of rasp 128. Rasp 128 may include opening 70, slot 76, andhole 130. Rasp 128 may couple with a shaft of a shaft assembly. Hole 130may receive a portion of a connector of the shaft. Opening 70 may allowrasp 128 to pivot relative to the shaft of the shaft assembly.

Rasp 128 may include posterior side 132 and anterior side 134. Sides132, 134 may be curved. Sides 132, 134 may have substantially the samecurvature as a spinal implant to be inserted in a disc space formedusing the rasp. In some embodiments, the curvature of posterior side 132may be substantially the same as the curvature of anterior side 134. Insome embodiments, the curvature of posterior side 132 may be differentthan the curvature of anterior side 134. In some embodiments, posteriorside 132 may have a smaller radius of curvature than anterior side 134.In some embodiments, posterior side 132 and/or anterior side 134 mayinclude no significant curvature.

Distal end 136 of rasp 128 may be tapered and/or curved. Tapered and/orcurved surfaces of distal end 136 may facilitate insertion of rasp 128in a disc space. In some embodiments, the tapered and/or curved surfacesof distal end 136 may be textured. The textured surface may facilitateremoval of intervertebral disc material during use. In some embodiments,distal end 136 may not be tapered and/or curved. Proximal end 138 ofrasp 128 may be blunt and/or rounded. In some embodiments, upper surface72 and lower surface 74 of rasp 128 may be angled relative to eachother. Angled upper surface 72 and lower surface 74 may facilitateremoval of intervertebral disc material during use.

Upper surface 72 and lower surface 74 of rasp 128 may be textured toabrade and/or cut vertebral bone. Texturing may be provided by methodsincluding, but not limited to, sanding the surface, forming grooves inthe surface, shot peening the surface, scoring the surface using anelectrical discharge process, and/or embedding hard particles in thesurface.

Rasp 128 may include teeth 80. Teeth 80 may engage cooperating elementsof a slide of a shaft assembly to secure a position of rasp 128 relativeto the shaft. Teeth 80 may allow an angle of rasp 128 relative to ashaft to be selectively set in range R. In some embodiments, range R maybe at least about 90°. In some embodiments, range R may be about 150°,about 120°, about 90°, or about 45°. Slot 76 may allow rasp 128 to beseparated from the shaft assembly when a portion of the shaft is alignedwith slot 76. Slot 76 may be located on rasp 128 such that the portionof the shaft cannot be aligned with slot 76 when the rasp is positionedbetween vertebrae in a patient.

In an embodiment, an end member may be a trial member used to evaluatesize and/or shape of a disc space. FIGS. 15 and 16 depict top and frontviews, respectively, of trial member 140. Trial member 140 may includevarious tapered, curved and/or flat outer surfaces. Trial member 140 mayinclude opening 70, slot 76, and hole 130 that allow the trial member tobe removably coupled to a shaft of a shaft assembly. Slot 76 may belocated on trial member 140 such that the shaft of the shaft assemblycannot be aligned with slot 76 when the trial member is positionedbetween vertebrae in a patient. Trial member 140 may include teeth 80.Teeth 80 may allow the trial member to be set at a desired anglerelative to the shaft of the shaft assembly. Trial member 140 mayinclude marker 142. Marker 142 may be color coded or include indicia toindicate to which instrument set the trial belongs.

An instrument set may include trial members of various sizes. Theinstrument set may include a trial member for each spinal implant sizeincluded in the instrument set. In some embodiments, a trial member mayhave the same dimensions as the dimensions of a corresponding spinalimplant. In some embodiments, one or more dimensions of a trial membermay differ from those of a corresponding spinal implant. For example, aheight of each trial member may be undersized relative to a height of acorresponding spinal implant for each trial.

In an embodiment, an end member may be a tamp used to position a spinalimplant in a disc space. FIGS. 17 and 18 depict top and front views,respectively, of tamp 144. Tamp 144 may include opening 70, slot 76, andhole 130 that allow the tamp to be removably coupled to a shaft of ashaft assembly. Slot 76 may be located on tamp 144 such that the shaftof the shaft assembly cannot be aligned with slot 76 when the tamp ispositioned between vertebrae in a patient. Tamp 144 may include teeth 80that allow the tamp to be set at a desired angle relative to the shaftof the shaft assembly. Tamp 144 may include end face 146 and tips 148.End face 146 may contact a spinal implant that is partially insertedinto a disc space. An instrument formed of a shaft assembly and tamp 144may be pushed or impacted with a mallet to advance the spinal implantinto a desired position in a disc space.

End face 146 may include any of a variety of profiles, including, butnot limited to, flat, convex, concave, arcuate, wedge-shaped, u-shaped,or yea-shaped. End face 146 may have various surface contours,including, but not limited to, smooth, textured, or padded. In certainembodiments, a tamp may include elements such as tabs, pins, orprotrusions for engaging a portion of a spinal implant. Such elementsmay facilitate manipulation of the spinal implant with the tamp. Forexample, tips 148 (shown in FIG. 17) on tamp 144 may engage a groove ornotch on a spinal implant to facilitate placement of the spinal implantusing the tamp.

FIGS. 19A-19D depict coupling of end member 54 with shaft assembly 52.Pin 64 may be aligned with hole 130 (shown in FIGS. 13-18). As depictedin FIG. 19A, distal portion 68 of shaft 56 may be aligned with slot 76.Pin 64 and distal portion 68 may be placed in slot 76. FIG. 19B depictspin 64 may engaged with hole 130 (shown in FIGS. 13-18). End member 54may be pivoted about pin 64. As depicted in FIG. 19C, distal portion 68of shaft 56 may be positioned in opening 70 away from slot 76. Slide 58may be translated toward end member 54. As depicted in FIG. 19D, teeth78 on distal end 66 of slide 58 may engage teeth 80 of end member 54.Engagement of teeth 78, 80 may inhibit rotation of end member 54relative to shaft assembly 52.

In an embodiment, an instrument may be used in a procedure to insert aspinal implant in a disc space between adjacent vertebrae. The spinalimplant may replace all or a portion of an intervertebral disc that hasdegenerated due to wear, trauma, and/or disease. The spinal implant mayrestore a normal separation distance between adjacent vertebrae andpromote fusion of the vertebrae. In certain embodiments, a spinalimplant may be inserted in a space formed between two portions of a boneto extend the length of the bone.

A discectomy may be performed to remove disc material from a disc space.A distractor may be positioned in the disc space to establish aseparation distance between the vertebrae. A disc space may be preparedusing instruments such as, but not limited to, scalpels, drills,curettes, chisels, or rongeurs. A chisel may be used to remove portionsof vertebral bone and form channels in the vertebral endplates adjacentto the disc space.

In some embodiments, an angle of an end member relative to a shaftassembly may be adjusted while the end member is in a disc space.Pivoting the end member may facilitate positioning of the end member invarious regions of the disc space. The ability to pivot an end membermay allow a user to maintain the shaft assembly of an instrument in adesired range without requiring a large working space. For example, anangle of the end member relative to the shaft assembly may be controlledsuch that a position of the shaft assembly is maintained in a relativelysmall range within a surgical opening in the patient at a surface of thebody as the end member is advanced in the disc space. The angle may beadjusted at selected points of advancement of the instrument into and/orwithdrawal of the instrument from a disc space. In one embodiment, anangle of an end member with respect to a shaft assembly is adjustedtwice during advancement of the end member and twice during withdrawalof the end member. In other embodiments, an angle of the end member withrespect to the shaft assembly is adjusted three or more times duringadvancement of the end member and three and/or more times duringwithdrawal of the end member.

In some embodiments, an end member may be allowed to pivot freelyrelative to the shaft assembly as the end member is withdrawn from anincision. The end member may deflect as the end member encounters tissueduring withdrawal. Pivoting of an end member during withdrawal mayreduce damage to tissue that might occur if the end member were lockedat a fixed angle during withdrawal of the end member.

Vertebral surfaces may require preparation before insertion of a spinalimplant in a disc space. A rasp may be inserted in an intervertebraldisc space from a posterior or transverse approach to abrade vertebralsurfaces. Vertebral surfaces may be abraded to remove osteophytes and/orto smooth rough surfaces. In some embodiments, an instrument with an endmember that is a rasp may be used to roughen vertebral endplates.Roughening of vertebral endplates may initiate a healing response thatpromotes bone growth. The bone growth may promote fusion of adjacentvertebrae with an installed spinal implant.

In an embodiment, an instrument including a rasp may be used to preparea disc space for a spinal implant. An angle of the rasp with respect toa shaft assembly of the instrument may be adjusted to facilitatepositioning of the rasp in the disc space. FIGS. 20A-20E depict use ofinstrument 50 including rasp 128. Rasp 128 may be placed in disc space150 at various angles relative to shaft assembly 52 of instrument 50.Vertebral surfaces may be abraded by moving shaft assembly 52 back andforth with rasp 128 in disc space 150.

An angle of rasp 128 relative to shaft assembly 52 may be selected toallow rasp 128 to be inserted in disc space 150 during a transverseapproach. After insertion, an angle of rasp 128 relative to shaftassembly 52 may be adjusted to allow instrument 50 to be positioned andused at different locations within disc space 150, including but notlimited to the area across midline of the vertebral body. Shaft assembly52 may be pivoted relative to rasp 128 by moving a slide of the shaftassembly and angling the shaft assembly relative to rasp 128. After adesired angle is obtained, the slide may be moved against rasp 128 tosecure the position of the rasp relative to shaft assembly 52. Rasp 128may be forced against an endplate of a first vertebra. Rasp 128 may bemoved to treat the vertebral surface of the first vertebra. Rasp 128 maybe forced against the endplate of a second vertebra. Rasp 128 may bemoved to treat the vertebral surface of the second vertebra.

A discectomy may be performed to remove a portion of an intervertebraldisc. The discectomy may form an initial path between vertebrae. Afterformation of the initial path, rasp 128 may be used to extend the pathin a desired trajectory. Referring to FIG. 20A, rasp 128 may beinitially secured in first orientation A relative to shaft assembly 52.Rasp 128 may be advanced in disc space 150 in an initial space formedduring a discectomy. With rasp 128 in disc space 150, shaft assembly 52may be adjusted from orientation A to orientation B. Frictionalengagement of rasp 128 with adjacent disc 152 may stabilize rasp 128sufficiently to allow shaft assembly 52 to be angled by moving a slideof the shaft assembly and angling the shaft assembly. After obtainingdesired angle B, the slide may be moved so that the slide engagescapture members of rasp 128. Rasp 128 may be used to extend disc space150 formed between vertebrae. FIG. 20B depicts a representation of disc152 after rasp 128 has been used to extend disc space 150. Shaftassembly 52 may be adjusted from orientation B to orientation C. Rasp128 may be further advanced into disc into 152 to establish desired discspace 150, as depicted in FIG. 20C.

Instrument 50 may be removed from disc space 150 by reversing the stepsused for insertion of the instrument. For example, with shaft assembly52 at orientation C, rasp 128 may be partially withdrawn from disc space150 (FIG. 20D). Shaft assembly 52 may be adjusted to orientation B. Rasp128 may be further withdrawn from disc space 150 (FIG. 20E). Shaftassembly 52 may be adjusted to orientation A, and instrument 50 may beremoved from the incision.

In an embodiment, an instrument including a trial member may be used togauge a disc space before insertion of a spinal implant. In an insertionprocedure that uses modular end members, a rasp may be removed from ashaft assembly after a disc space is prepared. A trial may be attachedto the shaft assembly. The instrument with the trial attached may beinserted into the disc space. The trial may have the same outer shape asthe shape of a spinal implant in an instrumentation set provided for thespinal implant insertion procedure. If the trial is easily inserted intothe disc space, the corresponding spinal implant may not have sufficientheight. If the trial cannot be inserted, the corresponding spinalimplant may have too much height. Insertion of the trial should beachieved with some impact on an end of the shaft assembly. The trial maybe fully inserted along the established disc space to ensure that thecorresponding spinal implant will be able to follow the same path. Theangle of the shaft assembly relative to the trial may be adjusted duringinsertion of the trial into the disc space. After complete insertion,the trial may be removed from the disc space.

In an embodiment, an instrument may be used to position, guide, and/ormanipulate a spinal implant in a disc space. FIGS. 21A-21D depictpositioning of spinal implant 156 in disc space 150. In someembodiments, bone growth promoting material may be placed in the discspace and/or in openings in the spinal implant to minimize or eliminategaps between the spinal implant and walls defining the disc space. Thebone growth promoting material may be, but is not limited to, autologousbone, allograft bone, xenograft bone, calcium phosphates, collagen,calcium sulfates, demineralized bone matrix, bone morphogeneticproteins, platelet derived growth factors, bone marrow aspirate, and/orblood. Spinal implant 156 may be placed in an initial position in discspace 150 using a spinal implant inserter 158 (FIG. 21A).

As depicted in FIG. 21B, instrument 50 with tamp 144 and shaft assembly52 may be coupled to spinal implant 156. Tamp 144 may be angled relativeto shaft assembly 52 in orientation A. Shaft assembly 52 may be advancedto drive tamp 144 and spinal implant 156 in disc space 150 (FIG. 21C).In certain embodiments, a mallet may be used to strike shaft assembly 52of instrument 50 to advance spinal implant 156 in disc space 150.

Shaft assembly 52 may be changed from orientation A to orientation Bwhile tamp 144 remains in place in disc space 150. In some embodiments,instrument 50 may be withdrawn slightly from spinal implant 156 tofacilitate angular adjustment. Tamp 144 may be secured to shaft assembly52 when the tamp is positioned in orientation B. Instrument 50 may beused to further advance spinal implant 156 into disc space 150. Tamp 144may be used to push spinal implant 156 fully into disc space 150. Aposition of spinal implant 156 may be monitored using radiologicaltechniques. After full insertion of spinal implant 156, instrument 50may be withdrawn from the surgical site.

In this patent, certain U.S. patents have been incorporated byreference. The text of such U.S. patents is, however, only incorporatedby reference to the extent that no conflict exists between such text andthe other statements and drawings set forth herein. In the event of suchconflict, then any such conflicting text in such incorporated byreference in such U.S. patents is specifically not incorporated byreference in this patent.

Further modifications and alternative embodiments of various aspects ofthe invention will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the invention. It is to beunderstood that the forms of the invention shown and described hereinare to be taken as the presently preferred embodiments. Elements andmaterials may be substituted for those illustrated and described herein,parts and processes may be reversed, and certain features of theinvention may be utilized independently, ail as would be apparent to oneskilled in the art after having the benefit of this description of theinvention. Changes may be made in the elements described herein withoutdeparting from the spirit and scope of the invention as described in thefollowing claims.

1. An instrument for use in spinal surgery, comprising: a shaft; an endmember rotatably coupled with the shaft, wherein the end member sconfigured to be positioned between vertebrae; and a slide coupled tothe shaft; wherein the slide is configured to selectively couple withthe end member to inhibit rotation of the end member with respect to theshaft.